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Offline tatfutureTopic starter

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HP 33120 ERROR
« on: October 09, 2019, 08:13:50 am »
HP 33120 TEST All Pass

HP 33120 TEST All Pass, but turning on the power, the more sine the flickering changes, the more the picture please help

SYNC changes with the frequency when adjusting the freq
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Offline tatfutureTopic starter

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Re: HP 33120 ERROR
« Reply #1 on: October 09, 2019, 08:17:03 am »
Please guide where to find
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Offline tatfutureTopic starter

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Re: HP 33120 ERROR
« Reply #2 on: October 09, 2019, 08:21:44 am »
checked all the components on the PCB look good - please help me
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Offline tatfutureTopic starter

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Re: HP 33120 ERROR
« Reply #3 on: October 09, 2019, 01:27:06 pm »
Please !!! Help me !!!
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Offline duak

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Re: HP 33120 ERROR
« Reply #4 on: October 10, 2019, 07:25:53 pm »
tatfuture, do you see any waveforms or changes in voltage with the oscilloscope on the +18V and -18V?

I don't have a manual or schematic.  Are there other DC power supply voltages you can show us?

What does the output signal look like on the oscilloscope when the horizontal timebase is set to slower speeds, say 10 ms and 1000 ms/cm?
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Offline mr.fabe

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Re: HP 33120 ERROR
« Reply #5 on: October 10, 2019, 10:55:57 pm »
Quote from: duak on October 10, 2019, 07:25:53 pm
I don't have a manual or schematic.  Are there other DC power supply voltages you can show us?
Now you do...

https://ese.wustl.edu/undergraduate/Documents/lab_support/HP_33120A_Function_Generator_Service.pdf
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Offline tatfutureTopic starter

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Re: HP 33120 ERROR
« Reply #6 on: October 11, 2019, 07:44:43 am »
Thank you duak






Please give me more guidance - thank you
« Last Edit: October 11, 2019, 08:08:36 am by tatfuture »
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Offline tatfutureTopic starter

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Re: HP 33120 ERROR
« Reply #7 on: October 11, 2019, 07:50:37 am »
Thank you mr.fabe
Please give me more instructions


Probably broken zener CR709 I do not have (DIODE-ZNR SMB 3.3V 5% 1W- 1SMB5913B) I am looking for equivalent zener
« Last Edit: October 11, 2019, 08:12:48 am by tatfuture »
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Offline mr.fabe

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Re: HP 33120 ERROR
« Reply #8 on: October 11, 2019, 08:00:00 pm »
Check the transistor at Q718 and the surrounding components.
852820-0
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Offline feedback.loop

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Re: HP 33120 ERROR
« Reply #9 on: October 12, 2019, 04:37:28 am »
Perhaps, this video might help.

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Offline tatfutureTopic starter

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Re: HP 33120 ERROR
« Reply #10 on: October 15, 2019, 02:42:44 am »
Thank you feedblack.loop
just as this video measures voltage Q718 is also 17.7 V but measuring transistors are good both-capacitor also good ..?

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